Articles with keyword: Gnomonic factor

Plimpton 322 Tablet as a Sumerian’s Ancient Boundaries Record
Raúl Pérez-Enríquez Departamento de Física Universidad de Sonora


Volume 3, Issue 2

 | pp.



One of the most astonishing tablets found in ancient Mesopotamia is the well-known Plimpton 322 Tablet. This tablet is a piece of clay recording fifteen rectangle triangles with integer number sides. It has been abundantly analysed and one of its most recent interpretations is that from Britton et al. (2011) who relate the Pythagorean triples with expert work of a scribe. They, also, assume the idea of covering the entire tablet with data including its reverse, which would include up to 23 rows with the corresponding triples. However, the only confirmed data are those of the obverse. Using the Joyce’s values for angles W of the corresponding triangles, in this paper, we consider that the triples can be visualized as gnomonic triangles (gnomons and their shadows at midday); then we suggest a new interpretation for the data appearing in the Tablet 322 of the Plimpton’s catalogue: they could represent a record of gnomonic locations of “boundary stones” (being W angles Latitudes) and consequently, they could be definitions of specific sites at the time of Sumerian world. The right triangles shown in the tablet could have been observed with a gnomon nearby cities like Terqa, Eshnunna, Akshak, Adab and Nippur in the northern part of Sumer, at the day of equinox around 4,000 years ago. Other cities to the north, outside this region, would be indicated by the other triples. If we assume that the origin of the Plimpton 322 tablet could be Larsa, a city nearby Uruk, then, we can suggest that a missing part of the broken tablet would include up to 70 mm of data (according to Britton et al.) of an additional column for the side (h) itself and a possible column for the place; at least two more rows: one for a triangle 875:1440:1685 at Latitude of Larsa and another corresponding a triangle 611:1020:1189 for Ur city. These last triples were found with a methodology based on the properties of Pythagorean triples of Plimpton 322 tablet and reported elsewhere: the h side must be a multiple of six.
Subjects:Archaeology, Modern Sciences in the Classics